COMPOSITION CONTAINING AN EPOXY RESIN AND A POLYKETONE

Abstract: Composition based on an epoxy resin, a multifunctional amine and a polyketone; process for preparing such composition comprising reacting a multifunctional amine with an epoxy resin and a polyketone; composition obtainable by such process, and laminate comprising a polyketone layer and an epoxy resin layer which are bonded with the help of a multifunctional amine.

Description: COMPOSITION CONTAINING AN EPOXY RESIN AND A POLYKETONE This invention relates to compositions containing polyketones and epoxy resin and to a process for preparing such compositions. Composite systems such as laminates, are employed in an increasing number of applications including piping, high pressure gas cylinders, and chemical storage tanks. For these applications, articles are formed by extrusion, blow molding, rotomolding, or some other conventional melt processing technique. In a second step, the one polymer is wrapped or coated with the other polymer. Typically, one of these polymers contains glass or carbon fibres. The result is a composite structure which can be readily fabricated into a wide variety of shapes and sizes, yet exhibits high strength in combination with the intrinsic properties of the substrate (i.e., impact, chemical and stress crack propagation resistance) . One of the critical design parameters which govern the ultimate properties of the composite structure is the strength of the interface. Strong interfacial bonds have the desirable characteristic of evenly distributing and transferring stress. Thus, strong interfacial bonds increase the service pressures and longevity of fabricated parts. It is preferred that the bond be formed at temperatures which do not melt or distort the existing part. It has been found that polyketone polymers react with primary amine functionalities at temperatures well below the melting point of the polyketone polymer. By using conventional curing conditions (around 150 to 180 °C) , a primary amine cured epoxy can form covalent bonds with the polyketone substrate. Due to steric hinderance, some amine curing agents are thought to more readily bond to polyketone polymers than others. The interfacial strength between the components of a composite system defines the ultimate properties which can be achieved. Yet when applying epoxy systems to a solid polyketone polymer substrate using conventional curing conditions, the interfacial bond is frequently insufficient to achieve the desired mechanical properties of the composite. The present invention now relates to a composition based on an epoxy resin, a multifunctional amine and a polyketone. Further, the present invention relates to a process for preparing a composition based on an epoxy resin, a multifunctional amine and a polyketone, which process comprises reacting a multifunctional amine with an epoxy resin and a polyketone. The compositions obtained have excellent bonding, and can be used in applications requiring the desirable properties of polyketone polymer and epoxy resins . The polyketone which is preferably used, is a linear alternating polymer of carbon monoxide and at least one olefinically unsaturated hydrocarbon. The polyketone can contain common polymer additives such as fillers, extenders, lubricants, pigments, plasticizers, and other polymeric materials can be added to improve or otherwise alter the properties of the compositions. The composition comprises polyketone and an epoxy resin. The epoxy resin component of the composition can be any curable resin having, on the average, more than one vicinal epoxide group per molecule. The epoxy resin can be saturated or unsaturated, aliphatic, cyclo-aliphatic, aromatic or heterocyclic, and may bear substituents which do not materially interfere with the curing reaction. Suitable epoxy resins are prepared from epichlorohydrin and a compound containing at least one hydroxyl group. The process will usually be carried out under alkaline reaction conditions. The epoxy resin products obtained when the hydroxy group-containing compound is bisphenol-A are represented below by structure I wherein n is zero or a number greater than 0, commonly in the range of from. 0 to 10, preferably in the range of from 0 to 2. Other suitable epoxy resins can be prepared by the reaction of epichlorohydrin with molecular di- and trihydroxy phenolic compounds such as resorcinol and phloroglucinol, selected polynuclear polyhydroxy phenolic compounds such as bis (p-hydroxyphenyl)methane and 4,4 '-dihydroxybiphenyl, or aliphatic polyols such as 1,4- butanediol and glycerol. Epoxy resins which are especially suitable for the practice of the invention have a molecular weight generally within the range of from 86 to 10,000, preferably from 200 to 1500. The commercially- available epoxy resin EPON Resin 828 (EPON is a trade mark) , a reaction product of epichlorohydrin and 2,2-bis (4-hydroxyphenyl- propane (bisphenol-A) having a molecular weight of about 400, an epoxide equivalent (ASTM D-1652) of about 185-192, and an n value (from formula I above) of about 0.2 is the preferred epoxy resin. The polyketone polymers which are employed as the major component of the composition are preferably linear alternating polymers of carbon monoxide and at least one olefinically unsaturated hydrocarbon. More preferably, the polymers contain substantially one molecule of carbon monoxide for each molecule of olefinically unsaturated hydrocarbon. The preferred polyketone polymers are copolymers of carbon monoxide and ethylene or terpolymers of carbon monoxide, ethylene and a second olefinically unsaturated hydrocarbon of at least 3 carbon atoms, particularly an x-olefin such as propylene. When the preferred polyketone terpolymers are employed as the major polymeric component of the blends of the invention, there will be within the terpolymer at least 2 units incorporating a moiety of ethylene for each unit incorporating a moiety of the second hydrocarbon. Preferably, there will be from 10 units to 100 units incorporating a moiety of the second hydrocarbon. The polymer chain of the preferred polyketone polymers is therefore represented by the repeating formula - [-CO- (-CH 2 —CH 2 -) -1 χ - [ CO- (-G)-] y - where G is the moiety of ethylenically unsaturated hydrocarbon of at least 3 carbon atoms polymerized through the ethylenic unsaturation and the ratio of y:x is no more than 0.5. When copolymers of carbon monoxide and ethylene are employed in the compositions of the invention, there will be no second hydrocarbon present and the copolymers are represented by the above formula wherein y is zero. When y is other than zero, i.e. terpolymers are employed, the —CO-(-CH2—1-2-)- units and the -CO-(-G)- units are found randomly throughout the polymer chain, and preferred ratios of y:x are from 0.01 to 0.1. Of particular interest are the polyketone polymers of number average molecular weight from 1000 to 200,000, particularly those of number average molecular weight from 20,000 to 90,000 as determined by gel permeation chromatography. The physical properties of the polymer will depend in part upon the molecular weight, whether the polymer is a copolymer or a terpolymer, and in the case of terpolymers the nature of the proportion of the second hydrocarbon present. Typical melting points for the polymers are from 175 °C to 300 °C, more typically from 210 °C to 270 °C. The polymers have a limiting viscosity number (LVN) , measured in m-cresol at 60 °C in a standard capillary viscosity measuring device, from 0.5 dl/g to 10 dl/g, more frequently from 0.8 dl/g to 4 dl/g. A preferred method for the production of the polyketone polymers is described in US-A-4,843,144, EP-A-314 309 and EP-A-391 579. The multifunctional amine molecules must be capable of reacting with both the polyketone substrate and the epoxy matrix. Compounds which have been found to be suitable include polymethylene diamines, diethyltriamine (DETA) , triethylenetetramine (TETA) , aminoethyl- ethanolamine, isophorene diamine, imidazoline, polyether diamines, carbohydrazide, adipic acid dihydrazide, amino-ethylpiperazine, and ethylenediamine. Multifunctional amine agents containing at least one unhindered alkyl primary amine are preferred especially in instances when the bonding/curing steps must be performed at temperatures below the polyketone melting point. The interfacial bond suitably can be achieved in two ways: (1) pretreatment of the polyketone (with or without a pre-cure step) or (2) inhibition of the multifunctional amine reaction via adjustment of the epoxy/amine stoichiometry and/or catalyst system. In lieu of reformulating the epoxy for optimum adhesion to polyketone polymer, the first method is preferred as it is thought to lead to better mechanical and chemical resistance properties as well as reduced curing times. The preferred method of affecting a strong interfacial bond between epoxy and polyketone involves a pretreatment of the polyketone. Here, the polyketone is reacted with a multifunctional amine to obtain a functionalized polyketone containing (partly) unreacted multifunctional amine. The functionalized polyketone is then reacted with an epoxy resin. This preparation process can be carried out by coating the polyketone with a solution or a finely divided solid containing at least one multifunctional amine. Once coated, the substrate can be heated to an elevated temperature (typically above 100°C) for a period of time which is sufficient to induce the polyketone polymer/amine reaction. Such pretreatment step produces a polyketone polymer surface with bonded moieties having available functionalities which are capable of reacting with the epoxy. The solid/solution is preferably evenly distributed along the polyketone substrate surface. The time and temperature of the pretreatment step is dependent upon several factors which include the degree of hinderance of the multifunctional amine, the mobility of amine and polyketone substrate, and the presence of catalyst systems. Non-branched, aliphatic primary amines exhibit a sufficient degree of reaction with the solid polyketone at temperatures above 100°C. Less reactive, more hindered amine functionalities require longer periods of time and/or higher temperature to induce a sufficient degree of reaction. Several catalyst systems could be envisioned which would accelerate the rate of reaction to reduce the time/temperature requirements of the pretreatment step. A general class of catalyst systems include weak acids and bases. The pretreatment reaction can also be accelerated by using a solvent carrier for the amine functionalized system which partially swells and plasticizers the polyketone. The plasticized polyketone would facilitate the reaction of the amine system. Swelling solvents for the polyketone include strong hydrogen bonding systems such as phenolics, alcohols, glycols, partially halogenated hydrocarbons, and the conventional aprotic solvents such as n-methyl pyrrolidone. However, non-aqueous solvents are preferred. After the pretreatment, the interfacial bond can be developed during the conventional cure cycle for the epoxy. During this process, remaining functionality of the molecules bonded to the polyketone surface can become integrated into the epoxy network via any number of known epoxide reactions. The recommended curing cycle for the epoxy resin system is that which is sufficient to promote reaction and bonding with the functionalized polyketone. It is also possible to achieve the interfacial bond without the elevated temperature pretreatment step, e.g. by applying the epoxy resin over the modified polyketone. In such a case, the interfacial bond can be actuated during the conventional curing protocol for the epoxy resin. Another method to achieve the strong interfacial bond involves reacting an epoxy resin with a multifunctional amine to obtain a functionalized epoxy resin containing (partly) unreacted multifunctional amine, and reacting the functionalized epoxy resin with a polyketone. The functionalized epoxy resin can be obtained by inhibiting the rapid consumption of curing agent from the reaction with the epoxy during the cure step. This can be accomplished by (1) using an imbalanced epoxy/multifunctional amine stoichiometry which favours r the amount of multifunctional amine in the system, and/or (2) employing a less effective catalyst system. In both cases, the potential for a reaction of the multifunctional amine with the polyketone substrate during a conventional curing protocol would be improved. However, the reformulation of these resins for optimal adhesion performance may in turn have detrimental effects on the mechanical and chemical resistance properties of the cured system. Further, the present invention relates to compositions obtainably by a process as described above, and to laminates comprising a polyketone layer and an epoxy resin layer which are bonded with the help of a multifunctional amine. EXAMPLES The invention was demonstrated by comparing the adhesive strength of epoxy-polyketone bond both with and without the pretreatment of the polymer surface. The pretreatment was executed by applying an isophorene diamine to the surfaces of injection molded plaques made from polyketone. The isophorene diamine was applied as a thin coating using a towelette saturated with the liquid diamine. The coated and control plaques were then placed in a nitrogen purged oven for 1 hour at 120°C. After removal from the oven, the treated and untreated plaques were bonded together using EPON 828 (EPON is a trade mark) with an isophorene diamine curing agent used at 23 phr. The cure cycle was as follows: 1 hour at 120 °C and 1 hour at 160 °C. After curing, the plaques were cut to form lap shear specimens using the procedure described in ASTM D1002 with a crosshead speed of 1.3 x 10-^ m/min (0.05 in/min) . Table 1. Lap shear strength of epoxy/polyketone polymer bond with pretreated and untreated polyketone substrates. As shown in Table 1, the lap shear strength of the pretreated materials significantly exceeds that of the untreated materials . The lap shear strength of the values encompassed in this invention are > 62 x 10 5 N/m 2 (900 psi).

Claims: C L A I M S 1. Composition based on an epoxy resin, a multifunctional amine and a polyketone. 2. Composition according to claim 1, in which composition the polyketone is a linear alternating polymer of carbon monoxide and at least one olefinically unsaturated hydrocarbon. 3. Composition according to claim 1 or 2, in which composition the epoxy resin is prepared from epichlorohydrin and a compound containing at least one hydroxyl group. 4. Composition according to any one of claims 1-3, in which composition the multifunctional amine contains at least one unhindered alkyl primary amine. 5. Composition according to any one of claims 1-3, in which composition the multifunctional amine is polymethylene diamine, diethyltriamine, triethylenetetramine, aminoethylethanolamine, isopherene diamine, imidazoline, polyether diamine, carbohydrazide, adipic acid dihydrazide, aminoethylpiperazine and/or ethylenediamine. 6. Process for preparing a composition based on an epoxy resin, a multifunctional amine and a polyketone, which process comprises reacting a multifunctional amine with an epoxy resin and a polyketone. 7. Process according to claim 6, which process comprises reacting a polyketone with a multifunctional amine to obtain a functionalized polyketone containing (partly) unreacted multifunctional amine, and reacting the functionalized polyketone with an epoxy resin. 8. Process according to claim 6, which process comprises reacting an epoxy resin with a multifunctional amine to obtain a functionalized epoxy resin containing (partly) unreacted multifunctional amine, and reacting the functionalized epoxy resin with a polyketone. 9. Process according to any one of claims 6-8, which process comprises reacting the multifunctional amine in the presence of a catalyst selected from the group consisting of weak acids or bases. 10. Composition obtainable by a process according to any one of claims 6-9. 11. Laminate comprising a polyketone layer and an epoxy resin layer which are bonded with the help of a multifunctional amine.

Inventors: ASH CARLTON EDWIN, WEINKAUF DONALD HILL, ASH, CARLTON, EDWIN, WINKAUF, DONALD, HILL
Applicants: SHELL INT RESEARCH, SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V.
Application year: 1994
Main classification: C08L73
IPC codes: B32B27, C08G59, C08G73, C08J5, C08J7, C08L63, C08L73